The Segway may not have set city trails ablaze, they have sparked plenty of DIY versions. A Segway is a costly transportation method since they cost as much as an entry level car. So, if you are tempted to build one of your own, follow this DIY Segway project and build one for a little over $400.
The motors, wheels, chain, gears and batteries were sourced from cheap electronic scooters. The electronics behind the DIY Segway are all custom. The main board is powered by an Atmel microcontroller and gathers data from the gyroscope, accelerometer, etc. The complete project details and build logs will aid you in creating one of your own.